车地通信中的分集合并技术与实现研究

【作者】 龙柯宇；

【导师】 唐斌；

【作者基本信息】 电子科技大学 ， 信息获取与探测技术， 2007， 硕士

【摘要】 高速磁悬浮列车控制指挥系统需要实时与列车交换重要的伺服及定位信息,可靠而高效的车地通信系统是保证列车指挥调度、运行安全的关键。因此,车地无线通信系统必须在干扰及衰落信道环境中实现可靠的实时数据传输。为了满足列车控制指挥系统的苛刻要求,车地通信系统必须采用特殊的抗衰落措施以提高数据传输的可靠性。在诸多抗衰落措施中,分集接收技术是车地通信系统改善可靠性的最为有效的措施。本文围绕车地无线通信系统中的分集合并模块的研制,在方案设计、论证、关键模块的研究实现以及系统联调等方面完成了以下工作:1.分析了磁悬浮列车车地无线通信系统的结构与特点,根据车地通信系统设计需要,明确了分集合并模块的任务及设计要求。2.介绍了毫米波多径衰落信道环境及抗衰落技术,在此基础上对分集合并技术进行了比较和分析,得出工程实践中必须遵循的基本原则。3.通过对分集合并模块的任务环境进行分析,并结合车地无线通信系统的结构特点研究了三种分集合并方案:基于选择性合并与最大比合并混合的两级合并方案、基于选择性合并与最大比合并混合的三级合并方案和基于模拟接收机的两级选择性合并方案。针对磁浮列车车地通信系统实际应用环境,对以上方案进行了详细的比较和分析,给出了工程可行的分集合并方案。4.对分集合并中的时延校正、信噪比估计等关键技术进行了研究,提出了易于硬件实现的基于位相关检测的数据质量估计方法,计算机仿真和实际系统的开发应用证明了该方法的有效性和可行性。5.完成了分集合并模块硬件平台的开发,将提出的分集合并方案应用于实际系统中,并给出了基于两级选择性分集合并方案的FPGA实现细节及设计要点。讨论了分集合并模块在测试现场实际应用过程中所遇到的具体问题和相应的解决方案。最后通过对现场调试数据与实际运行状况的分析,证明了本分集合并模块方案可行,能有效提高车地无线传输系统的通信可靠性,达到了预定的设计要求。更多还原

【Abstract】 The control and command system of high-speed maglev train needs to exchange important positioning information and servo data with the train. An efficient and reliable train-ground communication system is the key to insure the safety of the train. Therefore, it must achieve reliable and real-time transmission in interference and fading channel environment. In order to meet the request of the control and command system of the maglev train, special measures are used against the decline to improve the reliability of data transmission in the design of train-ground communication system, and the diversity reception technology is the most effective measure to improve the reliability of the train-ground communication system.Focusing on the development of diversity-combining module used in the train-ground communication system, the diversity-combining system as well as its key technology are discussed, and the design scheme of diversity-combining module is proposed and confirmed. Furthermore, both hardware and software of diversity combining module are developed.1. The train-ground communication system with the characteristics of the structure is analyzed. According to the demands of system design, tasks and design requirements of module are given.2. The millimeter wave multipath fading channel environment and the anti-multipath technology are introduced. On the basis of them, comparison and analysis of the combining techniques are provided, and basic principles in practice engineering are proposed.3. Based on the analysis of the requirements and characteristics of the train-ground communication system, three design schemes are researched, namely two steps combination scheme using a maximum ratio combination and a selective combination, three steps combination scheme using a maximum ratio combination and two selective combinations, two steps combination scheme only using two selective combinations. Aiming at the real environment, detailed comparison and analysis of these schemes is provided. 4. The key technologies which include time delay correction and signal-to-noise ratio estimation are researched in diversity-combining system. Data quality estimation method using bit correlation detection is proposed and verified.5. Hardware platform design for diversity-combing module is developed, schemes aforementioned are applied to practical system and FPGA design features are provided. The specific problems encountered in real testing field and the corresponding solutions are discussed. Finally, the analysis of test data in system testing shows that the module can improve the transmission performance effectively.更多还原